1. Field of the Invention
The present invention is directed to a hydrodynamic torque converter with a converter housing, a turbine wheel arranged in the converter housing that is rotatable with respect to the converter housing about a rotational axis, and a lockup clutch via which a torque transmission connection is producible between the converter housing and the turbine wheel, wherein the lockup clutch has a first friction surface arrangement which is held by a first friction surface carrier arrangement with respect to the converter housing so as to be substantially fixed with respect to rotation relative to it, a second friction surface arrangement which is held by a second friction surface carrier arrangement with respect to the turbine wheel so as to be substantially fixed with respect to rotation relative to it, a contact pressing arrangement operative for pressing the first and the second friction surface arrangement against one another in frictional contact, and an abutment arrangement at which the first and second friction surface arrangement can be supported substantially in the direction of the axis of rotation when acted upon by the contact pressure arrangement and which optionally forms at least one part of one of the friction surface arrangements.
2. Description of the Related Art
A prior art hydrodynamic torque converter with a lockup clutch having a first friction surface arrangement, a second friction surface arrangement, a contact pressing arrangement and an abutment arrangement is disclosed in German reference DE 197 24 973 C1. A lockup clutch of this torque converter comprises an outer plate set (first friction surface arrangement) and an inner plate set (second friction surface arrangement). The outer plate set is joined, via an outer plate carrier, to the converter housing so as to be fixed with respect to rotation relative to it, but is held therein so as to be axially displaceable. The outer plate carrier is constructed as a substantially annular structural component part which is welded by one axial end face to an inner surface of the converter housing. A toothing is formed by non-cutting shaping at an inner surface of the outer plate carrier, wherein corresponding teeth or projections at the outer plates and an abutment part engage in this toothing to provide a rotational coupling.
A problem arising in torque converters of the type mentioned above is that the welding process for connecting the outer and inner plate carriers requires carrying out subsequent machining procedures, e.g., reworking in the area of the weld. Another problem is that the design of the torque converter must allow fluid to pass through the lockup clutch even when a torque transmission connection is produced via the lockup clutch. Accordingly, openings must be introduced in the outer circumferential area of the outer plate carrier in this known torque converter which constitutes an additional work step which is difficult to carry out.
It is the object of the present invention to provide a hydrodynamic torque converter in which ensures that fluid is allowed to pass through the lockup clutch and that is simple to assemble.
According to the invention, the object is met by a hydrodynamic torque converter with a converter housing, a turbine wheel which is arranged in the converter housing and is rotatable with respect to this converter housing about a rotational axis, and a lockup clutch for producing a torque transmission connection between the converter housing and the turbine wheel, wherein the lockup clutch comprises a first friction surface arrangement which is held by a first friction surface carrier arrangement with respect to the converter housing so as to be substantially fixed with respect to rotation relative to it, a second friction surface arrangement which is held by a second friction surface carrier arrangement with respect to the turbine wheel so as to be substantially fixed with respect to rotation relative to it, a contact pressing arrangement for pressing the first and the second friction surface arrangements against one another in frictional contact, and an abutment arrangement at which the first and second friction surface arrangement are supported substantially in the direction of the axis of rotation when acted upon by the contact pressure arrangement and which optionally forms at least one part of one of the first and second friction surface arrangements.
It is further provided that the first friction surface carrier arrangement has a substantially annular body region connected with the converter housing or with a component connected with the converter housing. Driver projections are arranged at a distance from one another in the circumferential direction proceeding from the body region, wherein respective counter-driver projections at the first friction surface arrangement engage between these driver projections.
According to the present invention, the outer plate carrier, i.e., the first friction surface carrier arrangement, is not constructed as an axially continuous annular part. Rather the annular area of the annular body is limited to a certain length and driver projections proceed from this length, wherein gaps are formed between the driver projections. The fluid flowing into the interior of the converter is allowed to pass through these gaps. Furthermore, this through-flow is substantially not dependent on whether or not the lockup clutch is engaged. Accordingly, a suitable flow around the friction surface arrangements is ensured in every case, so that increased performance is achieved particularly when the lockup clutch slips.
The driver projections preferably extend approximately axially. Centering is achieved in the area of the lockup clutch in a particularly simple and accurate manner when an outer surface of the annular body region contacts an inner surface of the converter housing and/or a component connected therewith and the outer surface of the annular body region is connected with the converter housing and/or with the component connected therewith in the region of these surfaces.
For the axial support of the respective friction surface arrangements, the abutment arrangement, i.e., an abutment ring, may be supported at the driver projections in an end area of the driver projections remote of the annular body region.
Alternatively, the abutment arrangement may comprise a substantially annular abutment part with a radial outer region of the abutment arrangement secured to the converter housing and/or the component connected therewith. The radial inner side of the abutment arrangement forms an abutment area for the first and second friction surface arrangement. Accordingly, the abutment arrangement and the friction surface carrier arrangement are structural component parts that are separate from one another in this embodiment. This arrangement simplifies the construction of the individual structural component parts in themselves. In particular, the desired fluid passage may be maintained by introducing holes in the abutment arrangement.
The abutment ring may be connected with a substantially radially extending area of the converter housing and/or a component connected therewith to join the abutment ring to the converter.
The first friction surface carrier arrangement may assume a dual function. For example, the first friction surface carrier arrangement may form a radial supporting surface in the annular body region and/or an axial guide surface for the contact pressure arrangement.
In an alternative embodiment of the present invention, the object of the present invention is met in that the first friction surface carrier arrangement has an annular body region which forms the abutment arrangement and at which a connection area is provided in a radial outer region for connecting with the converter housing and/or with the component connected therewith.
In this case, the connection area may comprise a radial outer portion of the annular body region. A plurality of driver openings are formed in a successive arrangement along the circumferential direction in which respective counter-driver projections of the first friction surface arrangement engage to provide a simple rotational coupling of the first friction surface arrangement at the first friction surface carrier arrangement and to allow the desired flow of fluid.
In a modified embodiment form, a plurality of driver projections which preferably extend substantially axially are arranged at a distance from one another along the circumference and proceed from the annular body region. Respective counter-driver projections of the first friction surface arrangement engage between the driver projections.
To center the first friction surface carrier arrangement with respect to the converter, an outer surface of the driver projections may contact an inner surface of the converter housing and/or the component connected therewith.
In this embodiment, the driver projections may also form the connection area such that the outer surfaces of the drive projections are connected with the oppositely located inner surface of the converter housing and/or the component connected therewith. This connection is preferably by welding.
In addition to the driver projections, a plurality of fastening projections may also be arranged at a distance from each other along the circumferential direction in alternate succession with the driver projections and proceeding from the annular body to secure the first friction surface carrier arrangement to the converter. The fastening projections are secured to the converter housing and/or to the component connected therewith and form the connection area.
To ensure that the other components of the lockup clutch and particularly the friction surface arrangements are impaired as little as possible when carrying out the connection process and that those components ensuring the rotational driving of the first friction surface arrangement are unpaired as little as possible, the fastening projections extend substantially parallel to the driver projections such that outer surfaces of the fastening projections are at a greater radial distance from the axis of rotation than outer surfaces of the driver projections. The outer surfaces of the fastening projections are secured to an inner surface of the converter housing and/or to the component connected therewith.
In an alternative embodiment, the fasting projections may be secured to a surface region of the converter housing and/or of the component connected therewith that extends substantially radially or at a substantial inclination relative to the axis of rotation. This embodiment ensures that the friction surface arrangements are influenced as little as possible by the connection process.
In another embodiment the friction surface arrangement may be centered with respect to the converter with a positioning shoulder provided at the converter housing and/or at the component connected therewith. This embodiment permits a relative positioning of the first friction surface carrier arrangement wit respect to the converter housing.
Laser welding of the first friction surface carrier arrangement with the converter housing and/or with the component connected therewith ensures on the one hand that the connection process is carried out with high precision and, on the other hand, a deformation of the components to be connected with one another is prevented as far as possible by minimizing the heat energy introduced in the material to be welded. Therefore, it is unnecessary in practice to carry out any subsequent machining processes after the various components have been connected by laser welding.
The laser welding connection between the first friction surface carrier arrangement and the converter housing and/or the component connected therewith is preferably carried out at or proximite to a curvature area of the converter housing and the component connected therewith. The curvature area is preferably a transitional area between a substantially radially extending portion and a substantially axially extending portion of the converter housing and the component connected therewith. The location of the welding area in the area of surface regions which run into one another results in a focussing effect, especially for a laser welding process, which increases the efficiency of the welding process.
Furthermore, a supporting element may be provided in the torque converter according to the invention which supports a radial inner side of the contact pressure arrangement and/or on which the contact pressure arrangement is guided so as to be movable in the axial direction. The supporting element is secured by laser welding to the converter housing and/or the component connected therewith. Since this supporting element is also secured by laser welding, the connection process may be carried out simultaneously with the connection of the first friction surface carrier arrangement with the converter housing or with the component connected therewith.
The present invention is further directed to a friction surface carrier arrangement for a friction surface arrangement of a lockup clutch of a hydrodynamic torque converter, wherein the friction surface carrier comprises a substantially annular body region and a plurality of driver projections which proceed from the substantially annular body region and are arranged at a distance from one another in the circumferential direction and engage via a meshed engagement with counter-driver projections of the friction surface arrangement.
According to an alternative embodiment, the present invention is directed to a surface friction carrier arrangement for a friction surface arrangement of a lockup clutch of a hydrodynamic torque converter, comprising an annular body region having a radial inner area which forms an abutment arrangement for the friction surface arrangement and a radial outer area for securing to a component of the torque converter, wherein a plurality of driver openings constructed in the annular body region are arranged successively in the circumferential direction, wherein respective counter driver projections of a friction surface arrangement can engage in the driver openings.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects obtained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.